Analyzing the balance sheet of  Kelvin Enterprises, you observe current assets consisting of cash, marketable securities, accounts receivable, and inventory. Cash and marketable securities total $300,000, accounts receivable amount to $200,000, and inventory is valued at $400,000. Meanwhile, current liabilities include accounts payable, short-term loans, and accrued expenses. Accounts payable total $150,000, short-term loans amount to $100,000, and accrued expenses total $50,000. Compute the working capital.